Geothermal Energy and Maryland's Renewable Portfolio Standard (RPS)

Geothermal installations play a significant role in helping Maryland meet its Renewable Portfolio Standard (RPS) goals, which require the state to increase its use of renewable energy sources and reduce reliance on non-renewable resources. The RPS sets specific targets for renewable energy generation, aiming to reduce carbon emissions and promote environmental sustainability. Geothermal energy, as part of this renewable energy movement, offers several key benefits:

1. Increased Use of Maryland Renewable Energy

Geothermal systems, including Ground Source Heat Pumps (GSHPs), utilize the earth’s natural heat to provide heating and cooling for buildings. Unlike conventional HVAC systems, which often rely on fossil fuels or electricity generated from non-renewable sources, geothermal energy taps into a renewable, sustainable resource—the constant temperature of the earth. By harnessing this energy, geothermal installations contribute directly to Maryland's RPS goal of increasing renewable energy generation.

2. Reduction of Greenhouse Gas Emissions

The RPS in Maryland aims to decrease the state’s carbon footprint by transitioning to cleaner energy sources. Geothermal energy contributes significantly to this goal. By reducing the need for traditional heating and cooling systems that rely on electricity from fossil fuels, geothermal systems reduce the overall carbon emissions from buildings. Since GSHPs have a Coefficient of Performance (COP) of 3 to 6, meaning they can provide 3-6 units of heating or cooling for every unit of electricity used, they are incredibly efficient and environmentally friendly.

3. Energy Efficiency and Sustainability

In addition to being a renewable energy source, geothermal systems are highly energy-efficient. They require much less electricity than conventional systems, and their efficiency improves as they utilize the earth's naturally stable temperatures. The Maryland RPS incentivizes the adoption of energy-efficient technologies, and geothermal systems align perfectly with these incentives due to their high efficiency and low environmental impact.

4. Supporting Clean Energy Goals

Maryland’s RPS also includes specific targets for the integration of various clean energy technologies, including solar, wind, and geothermal. By investing in geothermal installations, homeowners and businesses in Maryland help meet the state’s renewable energy goals, advancing the transition to a more sustainable energy mix. Additionally, these systems may qualify for incentives and rebates offered under state programs that promote the adoption of clean technologies.

5. Long-Term Economic and Environmental Benefits

As the state continues to meet its renewable energy targets, the increased adoption of geothermal systems further supports Maryland’s broader economic and environmental goals. By reducing dependency on imported fossil fuels and lowering energy consumption through efficient systems, geothermal energy strengthens local energy security and promotes sustainable growth. This aligns with Maryland's goal of creating a clean energy economy and reducing reliance on non-renewable resources.

How GSHPs Work

Unlike traditional space heaters or electric baseboard heaters that directly convert electricity into heat, Ground Source Heat Pumps (GSHPs) utilize electricity to enhance and concentrate the natural heat stored in the ground. In the winter, electricity powers the system to circulate a fluid through underground pipes, absorbing the earth's stable heat and transferring it into a building. This process efficiently heats the building without the need for burning fossil fuels. During the warmer months, the system can reverse the process, drawing heat from the building and transferring it back into the ground, providing cooling.

What makes GSHPs particularly energy-efficient is their ability to move heat rather than generate it. For every unit of electricity used to operate the system, GSHPs can provide 2 to 6 units of heating or cooling, making them significantly more efficient than conventional heating methods. This efficiency is quantified by the Coefficient of Performance (CoP), a metric that measures how much heat is moved per unit of electricity consumed. By relying on the stable, renewable energy of the earth, GSHPs achieve an impressive energy efficiency that conventional systems can’t match, resulting in lower energy costs and a reduced environmental footprint.

How GSHPs Provide Heating and Cooling in Maryland

Ground Source Heat Pumps (GSHPs) are designed to provide both heating and cooling by transferring thermal energy between a building and the ground or a body of water. They work on a fundamental principle of heat transfer, which distinguishes them from traditional combustion-based heating appliances like furnaces, stoves, and boilers. Unlike these systems, which generate heat through the combustion of fuels such as natural gas, propane, fuel oil, or wood, GSHPs use electricity to move heat rather than create it.

In heating mode, a GSHP extracts heat from the ground or a body of water through a circulating fluid, which absorbs the earth’s stable, renewable heat. This heat is then compressed and transferred into the building’s heating system. The process is highly efficient because the temperature of the ground remains relatively constant throughout the year, providing a reliable and steady source of thermal energy.

When the temperature rises and cooling is required, GSHPs reverse the process. They transfer heat from the building’s interior into the ground or water body, cooling the space inside the home. This process is comparable to how a refrigerator works, where the appliance pulls heat from inside the fridge and expels it outside. The circulating fluid absorbs this heat from the building and is pumped back into the earth, where it is naturally dissipated, maintaining a cooler temperature inside.

In both heating and cooling modes, GSHPs rely on electricity to power a compressor and a pump that facilitate the transfer of heat. This electricity, however, is just a small part of the overall energy equation. The "free" energy provided by the ground, in the form of geothermal heat, makes the system much more efficient than traditional electric or gas-powered heating and cooling methods.

Renewable Energy and GSHPs

GSHPs are considered a partially renewable energy technology because they harness energy from two renewable sources: the earth’s geothermal heat and solar energy. The heat stored in the ground is primarily a result of solar energy that has been absorbed and stored over time, with more heat being replenished in the warmer months. This makes the energy resource replenishable and sustainable. The heat that is harvested from the ground in the winter, when heating is required, is naturally replenished by the sun in the summer months, creating a cyclical, renewable system.

Moreover, when the system is used for cooling, the heat extracted from the building is returned to the ground, ensuring the environmental equilibrium is maintained. The transfer of heat back to the earth helps mitigate the urban heat island effect and prevents the accumulation of excess heat in the environment.

However, it's important to note that the electricity used to power the GSHP's compressor and pump is not always sourced from renewable resources. Unless the homeowner purchases renewable energy credits (RECs) or produces their own renewable energy via on-site wind or solar power systems, the electricity may come from non-renewable sources, depending on the utility provider's energy mix. That said, as the electricity grid becomes increasingly powered by renewable energy sources, a GSHP’s overall sustainability and renewable energy credentials improve.

Like many other electric heating and cooling systems, a GSHP becomes “greener” as utilities integrate more renewable energy into their fuel mix. By reducing reliance on fossil fuels, GSHPs contribute to the overall reduction of greenhouse gas emissions, making them an important part of a more sustainable and energy-efficient future.

What are the components?

GSHPs consist of three main parts:

• Ground loop heat exchanger embedded in the ground or a water source,

• Heat pump/compressor, appliance inside a home, and

• Distribution system that moves heat throughout a building.

The ground loop component is comprised of tubing that passes through the heat source/sink. (If used for heating, then the heat source is the ground; if used for cooling, the heat source is the building and the ground is a heat sink). The loops can be buried in the ground vertically or horizontally in various configurations. Loops can also be placed in a water body. Heat is transferred to or from the ground/water to a fluid. Both closed loop and open loop designs can be used. The heat pump and compressor move heat from/to the ground and “step it up” to a temperature usable for space heating through a refrigeration cycle.

In the cooling mode, the same refrigeration cycle is reversed to concentrate heat energy from the building interior, allowing energy transfer to the ground. Alternately, in some cooling systems, the refrigeration loop is bypassed, and the fluid transfers heat directly to the ground. The distribution system moves heat into or out of a building. GSHPs are compatible with many standard distribution systems, including some hydronic (e.g., in-floor heating) and forced air systems. In heating-dominated climates, low-temperature distribution systems are preferred.

Types of Ground Loops Available for GSHPs

As the adoption of Ground Source Heat Pumps (GSHPs) has grown across the United States, so too have the various options for installing a ground loop system. This is particularly true in rural areas, where ample space allows for more customization based on local geology, ground conditions, and the heating/cooling requirements of the building. There are three main types of ground loops used in geothermal installations: closed-loop systems, open-loop systems, and hybrid systems.

1. Closed-Loop Ground Systems

The most common type of ground loop, closed-loop systems involve the installation of high-density polyethylene (HDPE) pipes in a loop configuration. These pipes are filled with a heat-transfer fluid that circulates continuously through the system to absorb and release heat from the ground. Closed-loop systems can be installed in a variety of configurations, depending on the available space and the specific needs of the building.

There are two primary types of closed-loop systems:

• Horizontal Closed-Loop System: In this setup, pipes are laid out in horizontal trenches, typically 4-12 feet underground, where they absorb and release heat. The trench depth varies depending on factors such as soil type, water table depth, and frost depth. A horizontal system generally requires more land space for the installation of multiple trenches. A medium-sized home, for example, may need at least four trenches, each up to 100 feet in length. While this setup is cost-effective in areas with sufficient land, it can be constrained by the amount of space available for excavation and the maneuverability of excavation equipment.

• Vertical Closed-Loop System: When space is limited, such as in urban or developed areas, vertical wells are drilled to a depth of 100 to 400 feet, depending on the local geology. These vertical boreholes are connected to the heat pump system using U-bend pipes, which allow fluid to circulate from the surface to the bottom of the borehole and back again. Vertical systems require less surface area than horizontal systems, making them ideal for properties with limited yard space. Additionally, vertical loops can be installed beneath parking lots, driveways, or even landscaped areas without disrupting existing structures or aesthetics.

2. Open-Loop Ground Systems

Unlike closed-loop systems, open-loop ground systems use an aquifer, lake, or other water source as the medium for heat exchange. In these systems, groundwater is pumped directly from the source, passed through the heat exchanger in the heat pump, and then returned to the source. Open-loop systems are highly efficient since they take advantage of the natural thermal properties of groundwater, which typically has a stable temperature year-round. However, these systems are only viable in areas where a reliable water source is available, and local regulations may limit or prohibit the use of groundwater for geothermal heating and cooling due to concerns over water quality or sustainability.

3. Hybrid Ground Loop Systems

Hybrid systems combine elements of both closed- and open-loop systems, offering a flexible and customizable solution for certain installations. In a hybrid setup, the geothermal system may use a combination of groundwater and ground loops, depending on local water availability and soil conditions. For example, the system might use an open-loop for cooling during the summer months and a closed-loop system for heating in the winter. Hybrid systems can be particularly effective when a water source is available for part of the year but may not be sufficient or reliable throughout the entire year.

Source: U.S. Department of Energy

How to Design a Geothermal System

Designing a geothermal system involves selecting the optimal type of ground loop system based on several factors unique to your property. The key considerations include the size of your land, geological characteristics, climate, and the specific heating and cooling needs of your home or building. Let's break down the various considerations for choosing and designing a geothermal system that best suits your needs.

Site-Specific Considerations

The ideal type of geothermal ground loop system depends largely on the characteristics of your site. Each system has distinct requirements for space, access to water, and the types of materials used in the ground. The most common ground loop types—open-loop, horizontal, directionally-drilled, and vertical—each offer different advantages depending on your property’s layout and location.

Open-Loop Systems

Open-loop systems are among the most efficient, but they require access to a large water body or a groundwater source such as a well. These systems extract water from the natural source, circulate it through the heat pump, and then discharge it back into the same water body. Since open-loop systems rely on water quality and availability, they are ideal for properties near lakes, rivers, or aquifers. However, they may not be suitable in areas with limited water sources or where local regulations restrict the use of groundwater.

Horizontal Loop Systems

Horizontal loop systems require a large, open area to install the pipes. The system is typically installed in trenches, with pipes buried between 4-12 feet below the surface. This type of system works well in rural areas or properties with ample yard space but can be challenging in densely developed areas or places with limited space. The installation of multiple trenches—sometimes up to four or more, each at least 100 feet long—requires sufficient open land. Additionally, the depth of the trenches will depend on the soil type, water table depth, frost level, and other local conditions.

Directionally Drilled Loops

For properties with limited space, directionally-drilled loops offer a more compact alternative to horizontal systems. These loops are drilled deeper into the ground in a more vertical orientation but still require a fair amount of yard space for proper installation. This method is especially useful in areas where space for traditional horizontal systems is unavailable or impractical. While directionally drilled loops require less surface area than horizontal systems, they still need enough space to accommodate drilling equipment.

Vertical Loop Systems

In cases where space is severely limited, vertical loops are often the best option. These loops involve drilling vertical boreholes up to several hundred feet deep, often beneath areas such as parking lots, existing landscapes, or even driveways. Vertical systems are ideal for properties with limited yard space, and they are becoming more common in urban areas. Although the installation of vertical systems can be more expensive than horizontal systems, they provide an excellent option for homeowners with smaller properties.

Ground Recharge and Heat Transfer

Another crucial factor in the design of geothermal systems is ensuring proper heat recharge of the ground loop. In climates where winters are colder and the system is primarily used for heating, it’s important to consider whether the ground can recover its heat during the warmer months. Ground temperature can fluctuate, and excessive heat extraction in winter may deplete the ground's ability to effectively recharge, leading to inefficiency.

Using the system for cooling in the summer helps to return some of the extracted heat to the ground, but this may not always be enough to fully "recharge" the geothermal source. In addition to the cooling cycle, summer sunlight helps recharge the ground, so it's beneficial to ensure that horizontal loops are located in areas with minimal shading. Shade from large trees or buildings could prevent the ground from recharging properly, especially during the summer months when the system is not actively extracting heat.

In colder regions, the presence of snow pack in winter can provide an insulating effect on the ground. Snow helps to retain the heat beneath it, making it easier for the system to continue absorbing heat from the ground while shielding it from extreme cold. As a result, the effectiveness of geothermal systems in colder climates can be improved by the insulating effects of snow on the ground loop.

Permitting and Regulatory Considerations

When designing a geothermal system, understanding local permitting requirements is crucial. In many areas, installing a geothermal ground loop system, particularly an open-loop system, will require permits from local, county, or state authorities. The regulations vary widely by region, so it’s important to work with experienced professionals who understand the specific permitting requirements for your area.

• Closed-Loop Systems: These are generally the least complicated in terms of permitting, especially when they are installed in a yard or under the surface of a property. However, if the closed loop is installed in or near a water body, such as a pond or lake, you will likely need additional permits for water usage and protection.

• Open-Loop Systems: Since open-loop systems use water from wells, lakes, or aquifers, they often require more extensive permits from state or federal agencies to ensure compliance with water protection regulations. Local water rights laws, as well as environmental protection policies, may also influence the approval process.

• Vertical and Directionally Drilled Loops: Installing vertical loops requires specialized drilling permits, especially if they are being drilled to significant depths. Local municipalities may have specific rules about how deep these systems can be drilled and whether certain protected geological layers can be disturbed.

It's important to consult with local professionals who can help you navigate the regulatory and permitting process to ensure that your installation is compliant with all relevant laws and requirements.

How to Size a Geothermal System

Geothermal heat pumps (GSHPs) are typically sized based on the cooling capacity, measured in tons. One ton of cooling equals 12,000 BTU/hr. For instance, a 5-ton system can extract 60,000 BTU/hr from a space, but the actual heat delivered depends on the temperature of the fluid from the ground loop. In heating-dominated climates, GSHPs are sized according to the heating demand, while in cooling-dominated areas, the cooling needs dictate the size.

To properly size a GSHP, it must meet the building's heating or cooling demand during extreme weather conditions, such as the coldest winter day or hottest summer day. An oversized system can lead to higher initial costs and inefficiency, as it will cycle on and off frequently. Conversely, a properly sized system runs efficiently with long, steady cycles.

Factors like insulation, building size, window count, and local climate all influence the system size. Energy raters or installers typically perform these calculations using professional software like the Air Conditioning Contractors of America Manual J, which is far more accurate than using general rules of thumb. These calculations help ensure the system is neither too large nor too small for the building’s heating or cooling needs.

How to Get Started with Geothermal

Installing a Ground Source Heat Pump (GSHP) is a complex process that involves several key considerations, including proper system sizing, integration with your home’s distribution system, ground loop installation, and refrigerant handling. To ensure a successful installation and long-term performance, it’s essential to hire a qualified installer, as they will not only guarantee a high-quality installation but also keep your system’s warranty valid. Before making your decision, make sure to obtain multiple bids, keeping in mind that the lowest price may not always offer the best value or the most comprehensive warranty. Here's a detailed checklist to help you evaluate potential contractors:

Referrals and Licensing

• Personal Recommendations: Have you received a referral from a friend, coworker, or neighbor? If so, ask about their experience with the contractor.

• Experience with GSHPs: Does the contractor have experience installing

  GSHPs in your area? This can ensure they understand local soil, climate, and installation conditions.

• References: Can the contractor provide names of past clients you can contact for feedback?

• State Licensing: Verify whether your state requires contractors to be licensed for GSHP installations. You can ask the contractor directly or check the state's online database of licensed contractors.

• Insurance: Ensure the contractor is bonded and insured. They should provide proof of insurance for both liability and workers’ compensation.

• Certifications: It’s important that the contractor is certified by the International Ground Source Heat Pump Association (IGSHPA) or by a recognized manufacturer. This certification ensures they have received proper training in GSHP installation.

Building Evaluation and Sizing

• Building Assessment: Will the contractor inspect your building and the existing system to determine any necessary improvements? This inspection should take at least an hour to ensure a thorough evaluation.

• Sizing Calculations: Does the contractor use the Air Conditioning Contractors of America (ACCA) Manual J or similar software to calculate the heating and cooling needs of your home? Accurate sizing ensures the GSHP will perform efficiently and effectively.

• Previous System Review: If replacing an existing system, does the contractor review information from the previous system, such as maintenance records or fuel bills?

• Testing for Leaks: Will the contractor check for leaks in your distribution system both before and after any improvements? Both sets of results should be shared with you.

Equipment and Features

• Energy Star Certification: Does the contractor install GSHPs that are EPA ENERGY STAR-rated? These systems are more energy-efficient and can save you money in the long run.

• Documentation: Will the contractor provide manuals and warranty information for the installed heat pump?

• Additional Features: Is the contractor willing to install additional features like zoning or a programmable thermostat? They should also demonstrate how to use these features effectively.

• Maintenance and Schedule: Will the contractor explain the necessary maintenance tasks and help you set up a schedule for regular professional check-ups?

Proposal and Contracts

• Written Proposal: Does the written proposal include a timeline for installation and payment details? This helps you understand when the project will begin and be completed.

• Itemized Estimates: Is the proposal detailed, with itemized estimates of costs, so you can clearly see where your money is going?

• Incentives: Does the contractor know about available rebates and incentives that may reduce the installation cost? Many states offer financial incentives for energy-efficient home improvements.

• Permits: Will the contractor handle the required permits for system installation? This saves you time and ensures everything is up to code.

Ongoing Maintenance and System Longevity

Unlike traditional combustion-based heating systems, GSHPs require less frequent maintenance, making them safer and more efficient over time. These systems are designed to run quietly and continuously in the background, with minimal operation tasks needed from the homeowner. A GSHP typically has a lifespan of 25 years, with the ground loop lasting 50+ years. The high-density polyethylene pipes used in the loop are durable and leak-resistant, though in the rare event of a leak, it should be addressed promptly.

Routine maintenance may include changing air filters for forced-air systems and switching between heating and cooling modes. The contractor should help you establish a maintenance schedule and guide you through simple upkeep tasks. Additionally, the contractor can perform periodic check-ups to ensure that your system operates at peak efficiency.

In the rare case of a ground loop leak, solutions will depend on the type of system and the installation. Some contractors offer warranties on ground loops, so it’s beneficial to inquire about this when choosing an installer. At the end of the system's lifespan, refurbishing options may be available, although advancements in technology often make replacing the unit with a newer, more efficient model a better investment.

By carefully considering these factors, you’ll be on the path to making an informed decision for your GSHP installation, ensuring a long-lasting, energy-efficient, and cost-effective solution for your home.

For expert guidance, cost estimates, and installation services, contact Maryland Geothermal today! Don't hesitate to reach out if you have any questions regarding geothermal installations in Maryland. Contact us by phone (703) 719-8409 or email jake@northamericangeo.com.

Maryland Geothermal proudly serves communities across both Prince George and Montgomery counties, including Bowie, College Park, Greenbelt, Laurel, Hyattsville, Upper Marlboro, Glenarden, New Carrollton, District Heights, Mount Rainier, Riverdale Park, Seat Pleasant, Berwyn Heights, Bladensburg, Brentwood, Capitol Heights, Cheverly, Edmonston, Fairmount Heights, Forest Heights, Landover, Landover Hills, North Brentwood, North Bethesda, Mitchellville, Olney, Fort Washington, Glenn Dale, Bethesda, Clarksburg, Kensington, Rockville, Gaithersburg, Darnestown, Chevy Chase, and Potomac